Geometry extensions: remove unnecessary smart pointer deletion

==============================================================

When the geometry object is destroyed, std::vector's destructor is called, which in turn calls the destructor of the smart pointers.

If a weak_ptr corresponding to one of those shared_ptr is locked (elsewhere, if FC were multithread),
the underlaying resource will not be freed until said locked weak_ptr goes out of scope. It will then.

src/Mod/Part/App/Geometry.cpp

@@ -192,8 +192,7 @@ Geometry::Geometry()
 
 Geometry::~Geometry()
 {
-    for(std::vector<std::shared_ptr<GeometryExtension>>::iterator it = extensions.begin(); it != extensions.end(); it++)
-        (*it).reset();
+
 }
 
 // Persistence implementer